The Project 636 submarines (NATO reporting name: Kylo) are intended to destroy enemy submarines, surface combatant ships and vessels, protect naval bases, sea costs and lanes, carry out reconnaissance and land reconnaissance groups. These submarines were developed from the 877EKM submarines. Designers managed to resolve many problems by increasing the length of the inner hull by two frame spacings (600 mm x 2), thereby increasing the power of diesel-generators and mounting them on improved shock-absorbing support, reducing twofold the main propulsion shaft speed, etc. Owing to these improvements, the submarine speed and sea endurance were increased, while the noise level was radically decreased and other characteristics were improved. The low noise of the submarine was achieved owing to its streamlined configuration, special anti-sonar rubber coating applied to the outer hull, quiet operating mechanisms and other design improvements. Blended into natural marine sounds, the submarine is capable of detecting the enemy submarine at a range 3-4 times greater than its own detection and since it possesses powerful and accurate quick-action torpedo weapons, this submarine hits the enemy first in a duel. To increase its survivability, the submarine is partitioned into six compartments by robust transverse bulkheads. The submarine, featuring a 30 percent buoyancy, can keep afloat, even when one compartment with two adjacent tanks of one side ballast is flooded. The submarine is powered by a one-shaft power plant operating in a full electrically propelled mode. The main propulsion motor, economic run motor and seven-blade propeller of special design are arranged on the shaft line. In addition, there are two stand-by propulsion units that ensure the submarine's run in narrow waters, at mooring and in emergencies. Two 120 cell storage batteries of a new design are accommodated in the first and third compartments of the submarine. The submarine is automated and fitted with a torpedo tube quick-loading system. All torpedo tubes are accommodated in the nose part of the submarine. The torpedo tubes can launch mines in lieu of torpedoes. The submarine and its weapons are controlled from the main control room, isolated from other compartments. To enhance operational efficiency, the submarine CO controls the boat and torpedo firing via a multipurpose command-information control system (BIUS) incorporating a high-speed computer. The submarine is also equipped with state-of-the-art electronic, communications and navigational aids. The advanced ventilation and air-conditioning system can be optionally installed to suit the customer's choice. The submarine is also fitted with a new large capacity refrigerating system. The submarine technical facilities guarantee its reliable operation in any climatic conditions. The complement is 52 men. The crew is accommodated in comfortable cabins. The submarine also has a galley, shower, medical bay and officer's wardroom.